On 24 November 1498 Henry IV, Magnus and the latter's father John V, Duke of Saxe-Lauenburg allied in order to conquer the Land of Wursten, a de facto autonomous region of free Frisian peasants in a marsh at the Weser estuary, under the loose overlordship of the Prince-Archbishopric of Bremen.
[2] On 16 November, Prince-Archbishop Johann Rode of Bremen had prepared for this by concluding a defensive alliance with Hamburg, fearing for its military outpost Ritzebüttel at the Outer Elbe protecting free navigation from and to the city.
[4] By 20 November 1499 Magnus hired the so-called Great or Black Guard of ruthless and violent Dutch and East Frisian mercenaries, commanded by Thomas Slentz, recapturing Hadeln in early 1500.
[6] In return Rode offered to appoint Henry's 12-year-old son Christopher as his coadjutor, a position usually (as coadiutor cum iure succedendi), and in this case indeed, entailing the succession to the respective see.
[8] Rode and chapter had agreed to pay for Christopher's necessary papal dispensation from the canon-law age limit, as he was too young to be coadjutor, while Henry IV guaranteed military support for the prince-archbishopric.